The International Association of Plumbing and Mechanical Officials (IAPMO) Plumbing Technical Committee appointed a DWV Task Group to evaluate the sizing tables for drainage, waste and vent piping. The objective includes reviewing the current sizing methods for DWV systems and making recommendations based on past and present research and technology. This Task Group met twice to discuss the concept. After considerable debate, the Task Group decided to submit code changes on engineered sizing to Appendix L.
The current sizing of drainage and vent systems in the Uniform Plumbing Code (UPC) are based on historical data. The Task Group realized that, for many taller buildings, the pipe sizing increases indiscriminately. The proposed engineered sizing method would follow the provisions published in the American Society of Plumbing Engineers (ASPE) Plumbing Engineering Design Handbook.
Another concern expressed regarding the sizing of taller buildings was the lack of venting methods utilized in sizing branch intervals for stacks with more than three branch intervals, as well as the venting of offsets. However, with the larger pipe sizes, the venting of an offset is not as important. With the allowance for an engineered sizing method, however, offsets in high-rise buildings would need to be vented. This requirement is included in the proposed code change.
ASPE Also Proposes ChangesThe ASPE Legislative Committee proposed a series of code changes that would dovetail into the code changes proposed by the DWV task group. ASPE proposed code changes to Chapter 7 and 9 of the Uniform Plumbing Code that would specifically recognize engineered design of a drainage and vent system. The proposed new sections would reference both Appendix L and Section 301 of the code.
Appendix L contains the engineered design requirements. There has always been a question as to whether Appendix L is a part of the code, or whether it is a separate appendix that needs to be specifically adopted by a jurisdiction. IAPMO considers the provisions in the appendices to be intended to supplement the requirements of this code and are not considered part of this code unless formally adopted as such (see Section 101.4.3 of the 2006 UPC).
Section 301 provides text for approving an engineered plumbing design. This section informs both the inspector and the engineer what is required to be submitted for an engineered design. The section currently appears in the 2006 edition of the Uniform Plumbing Code.
There are two ASPE changes that clean up Appendix L. When bathroom group wet venting was added to Chapter 9, it was not removed from Appendix L. Additionally, when the updated circuit venting requirements were added to Appendix L, the older battery venting section was not deleted.
In the storm drainage chapter, ASPE proposed a code change to recognize its new standard, ASPE 45. This standard addresses the design of syphonic roof drainage systems. This would be the first inclusion of an ASPE standard in a plumbing code. While the standard is not yet in published form, it is anticipated that it will be available by the first meeting of the Plumbing Technical Committee.
The remaining ASPE code change may send shock waves through the plumbing industry. ASPE proposes to add a new section to Appendix L addressing the engineered design of air admittance valves. For years, the air admittance valve manufacturers have been trying, unsuccessfully, to add requirements to Chapter 9 of the Uniform Plumbing Code. The IAPMO Plumbing Technical Committee appointed a Task Group to report on recommendations and additional criteria regarding air admittance valves. These recommendations will be discussed and provided to the UPC Technical Committee in April. The IAPMO Plumbing Technical Committee appointed five task groups, including Standards Task Group, Correlation Task Group, DWV Task Group, FOG Task Group and AAV Task Group.
ASPE decided to propose the change since it addresses venting systems using air admittance valves in Volume 2 of the Plumbing Engineering Design Handbook. The proposed change contains requirements similar to the requirements in the Handbook.
By including the change to Appendix L, a system using air admittance valves would have to be designed by a registered design professional. Hence, the section would only apply to plumbing engineers. ASPE has not opposed the inclusion of air admittance valves in Chapter 9.
Surveys Say"ASPE also pointed out that, in a recent survey, a large majority of ASPE members (plumbing engineers) have designed DWV systems with air admittance valves. In the same survey, the engineers indicated their acceptance of the use of air admittance valves. ASPE was quick to point out that the survey was not a scientific survey. It was a poll of its members on the chapter level with a high number of returns.
In PM Engineer’s survey, which was verified by statistical analysis, there were similar results. The plumbing engineering community has no problem with the use of air admittance valves. Furthermore, the majority has included them in engineering designs.
This would not be the first time air admittance valves appear in the Uniform Plumbing Code. In the 2006 edition, air admittance valves are mentioned in Appendix L under the single stack venting section. Again, this design criterion is limited to plumbing engineers.
It is interesting, if not somewhat ironic, that ASPE has proposed a code change for use of air admittance valves, whereas, the American Society of Sanitary Engineering (ASSE) has never supported a single code change for air admittance valves. Of course, ASSE promulgates the two standards that regulate air admittance valves: ASSE 1050 and ASSE 1051. One would think that an organization that develops and publishes a standard would support that standard. But ASSE has never supported the air admittance valve standards.
Perhaps the code change submitted by ASPE will force the ASSE Board of Directors to take a serious look at their stance regarding their own standards. It looks rather foolish that ASPE has proposed a change, not ASSE. It will look even more foolish if ASSE sits on its hands at the IAPMO Plumbing Technical Committee meeting when ASPE presents the code change on air admittance valves.
It should also be noted that ASSE accepts money from eight manufacturers of air admittance valves to issue a seal for those products. If I were one of those manufacturers, I would be all over ASSE as to why it doesn’t support their certification program, yet it will take their money. It appears the manufacturers are not getting their money’s worth.
The first meeting of the IAPMO Plumbing Technical Committee and Mechanical Technical Committee will take place the week of April 23, 2007, in St. Louis, MO. This is the first meeting that the changes to the 2009 Uniform Codes will be discussed. For additional information on the meeting, go to www.iapmo.org.